Engine Rebuild – Do I need one ? – Will my vehicle be like new again ?

Engine Rebuild - Do I need one ? - Will my vehicle be like new again ?
Engine Rebuild - Do I need one ? - Will my vehicle be like new again ?

So, the most common reasons to do a engine rebuild are, loss of compression and or excessive engine oil consumption.

Consequently, what’s important now, is to recognize the signs of trouble, before you end up doing even more damage.

Engine Rebuild – Is It Worth It ? This may not be a easy question to answer. Fortunately, there are a few ways to narrow down where your problem(s) lies; without doing a complete teardown of your engine.

Above all, having to to an engine rebuild, is very expensive and time consuming. So, making the correct decision, is very important. Consequently, the following signs generally indicate, internal engine trouble, likely meaning a rebuild is in your near future.

Loss, Of Engine Compression

Low compression can stem from any type of internal engine problem; that allows the air-fuel mixture to escape from a cylinder or reduces volumetric efficiency.

Loss Of Engine Compression
Loss Of Engine Compression

The most common signs of low compression include:

Engine Misfires

Engine misfires are a common sign of low engine compression in one cylinder. These occur when the engine skips one of the processes of the combustion cycle. In the case of low compression, the compression process is skipped or sometimes not executed well.

Loss Of Engine Power

Besides making the engine run rough and the vehicle jerk as it moves, misfiring also leads to power loss. Power loss in an engine is directly proportional to the number of cylinders affected.

For instance, if 2 out of 4 cylinders are misfiring, there’ll be a 50% reduction in power. Sure, you may be able to take the car for a drive with a 25% power reduction. But, you likely won’t be able to drive in hilly/elevated terrains at the normal speed.

Poor Fuel Economy

The higher the compression ratio in a vehicle, the better its fuel economy will be, generally. It follows that when your car has low compression, fuel economy will be significantly affected. Your engine will burn up more fuel to cover a specific distance than it would in typical scenarios. If you notice reduced fuel economy, it’s a good idea to check for signs of low engine compression.

Engine Will Not Start

In case all engine cylinders have low compression, then your vehicle won’t start; no matter how hard you try to power it up. The reason for this is that your engine won’t have sufficient pressure to ignite the fuel-air mixture.

All of the signs above can be caused by lack of compression; but, they can also be caused by other things. So, before doing a engine rebuild, it should be confirmed, by performing a compression or leak down test.

Excessive, Oil Consumption

Above all, oil consumption is the loss of engine oil, even though there are no significant external oil leaks. So, excessive oil consumption, is the consumption or loss of oil; at a rate, that is faster than “normal.” What’s normal depends on the specific engine. Because, each one will have its own; recommended change interval and may burn oil, at different rates compared to other engines.

Excessive, oil consumption, can be caused by:

  • Worn valve guides.
  • Dried valve guide seals.
  • Stuck oil control rings.
  • Excessive cylinder to piston clearance.
Worn Piston Rings On Piston
Worn Piston Rings On Piston

The most common symptom of excessive oil clearances, is an awful knock coming from the engine. Low oil pressure, is also a symptom of, excessive oil clearances. But, is less common (by the time the oil pressure goes low there’s usually an engine knock evident).


Is It Worth It, To Repair Or Rebuild My Engine ?

Most of the time, it comes down to a personal choice. There is no easy solution, to the question. But, there are cases, where it’s an easy decision. If the car is 20 years old, with 300,000 miles on it and is falling apart at the seams; then it’s pretty obvious, it makes no sense to fix it. If the car is 5 years old and in good shape, it’s definitely worth fixing. Most of the cars that need engines, fall somewhere in-between.

Engine Rebuild
Engine Rebuild

Consider the total projected cost of the engine, plus any needed maintenance and repairs. Consider whether, you like your car or not; and the cost of buying a new or used car you would like. Keep in mind, that there is some uncertainty in buying a used car, even if you have it inspected. Remember to include financing costs and full coverage insurance, when thinking about a new car. In some cases, it is worth doing repairs to a car, in excess of its blue book value.

So, If I Do A Engine Rebuild, My Car Will Be Like New, Right ?

No: The car is much more, than just the engine. There’s steering, suspension, transmission, brakes, tires, axles, fuel injection, smog equipment, and a lot more. A car with a rebuilt engine, will still run poorly with bad ignition wires; and still fail a smog test, with a bad O2 sensor and still overheat, with a bad radiator.

How Do I Break In, A Rebuilt Engine ?

Vary the engine speed and load. Don’t use over 75% throttle. Never go over 75% of the maximum (RPM). On a flat tappet engine, don’t use synthetic oil. Never let the engine idle for extended periods. Don’t cruise on the freeway at the same speed for extended periods. It should only take about 500 miles to break an engine in. After that, change the oil and do what you want.

Believe it or not, how you break your engine in; can make a huge difference, in how long your rebuilt engine lasts and how much oil it uses. You should also be aware that; the rebuilt engine will burn more oil as it is breaking in, so check the oil frequently.


So, why did the engine fail in the first place ? This is important to consider. If your maintenance was spotty and you don’t change your habits; then the new engine, will fail as well. Finally, is usually is a, correctable reason for engine failure.

Thank You !